Yarn heating apparatus

ABSTRACT

Apparatus for continuous heating of linearly advancing textile yarns by means of a tube sealed at its ends in an enclosure containing a heated fluid medium, the tube having certain physical characteristics to provide a substantially constant wall temperature.

United States Patent 11 1 Raschle June 12, 1973 [54] YARN HEATINGAPPARATUS [56] References Cited [75] Inventor: Josef Raschle, 9606Buetschwil, UNITED STATES PATENTS Switzerland 2,820,280 l/l958 Benn57/34 HS 3,002,729 10/1961 Welsh 165/183 [731 Asslgneel l & 2,823,2922/1958 Kunzle 34/152 x swltlerland 2,896,060 7/1959 Serfass et al 34/152x Filed y 28 1971 2,900,783 8/1959 Carter et al 57/34 HS [21] Appl. No.:147,855 Primary Examiner-Carroll B. Dority, Jr.

' AttorneyJohn Thomas Cella [30] J 1207:5111 Apglieptioln :riority Data102 71 ABSTRACT I WI zer an "f Apparatus for continuous heating oflinearly advancing [52] us Cl 34/154 34/152 57/34 HS textile yarns bymeans of a tube sealed at its ends in an [51] Int Cl F126) 13/00enclosure containing a heated fluid medium, the tube [58 1 Field 4/41152 having certain physical characteristics to provide a sub- 34/154,5784 HS stantially constant wall temperature.

8 Claims, 6 Drawing Figures YARN HEATING APPARATUS This inventionrelates to apparatus of heating continuously advancing lengths for yarnconsisting at least partially of thermoplastic material. Moreparticularly, the invention relates to a tubular heater constructed toafford a very nearly uniform temperature throughout its length.

For uniformly and homogenously heating textile filaments and yarns ofusual titers, apparatuses with tubeshaped members are known in which theheat radiated from the heated walls of the tubes is transferred to theyarns. Such heating tubes are used particularly in falsetwistingmachines for 'texturing synthetic thermoplastic textile yarns forheat-setting the false-twist. A known apparatus of this type consists ofan enclosure containing a heated gaseous medium and in which a number ofsteel tubes through which the yarns pass in axial direction are arrangedin axial parallelism, the tubes being heated by the gaseous medium.Since the length of the these tubes is limited by the space availablewithin the treatment machine, i.e., as a rule not more than 1 m, it isessential to supply to the yarn as much radiated heat as possible overthe entire length of the tube, i.e., in the optimal case, the walls ofthe tube should be at the same temperature over their entire length.With steel tubes used in the know apparatus, having a usual wallthickness and interior diameter, this optimal condition is not reached,but rather, as a rule, a considerable temperature decrease exists at theextremities of the tube, particularly at the lower extremity, it beingusual to mount the tubes axially vertically. Additional heatingapparatus embodying similar disadvantages is shown in U.S. Pat. No.3,085,390.

It is the purpose of the present invention to avoid this disadvantageand to produce a heating tube having a wall temperature as constant aspossible over its entire length.

The object of the invention, therefore, consists in an apparatus forheating continuously moving textile yarns consisting at least partiallyof synthetic thermoplastic material by means of heating tubes arrangedin an enclosure containing a heated fluid medium, the yarns passing inaxial direction through the tubes. The apparatus of the invention ischaracterized in that the walls of the tubes consist of a material of aheat conductivity of at least 70 kcal d T C, where d distance in meters,T time in hours and C temperature in celsius degrees, that the interiordiameter of the tubes is not over 4 mm and that the wall thickness is atleast 2.5 mm. In a preferred embodiment, the walls of the tubes mayconsist of aluminum, the interior diameter of the tubes may be 2.5 3.5mm, and the thickness of the tube walls between 3 and 5 mm. Furthermore,the outer faces of the tube walls may be formed with ribs in order toimprove heat transfer from the fluid medium to the tube wall.

There has thus been outlined rather broadly the more important featuresof the invention in order that the detailed description thereof thatfollows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject of the claims appended hereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based for the designing of other structures for carryingout the several purposes of the invention. It is important, therefore,that the claims be regarded as including such equivalent construction asdo not depart from the spirit and scope of the invention.

A specific embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings,forming a part of the specification wherein:

FIG. 1 is an elevational sectional view of a known heating tube;

FIG. 2 is a view similar to that of FIG. 1, but illustrating a heatingtube according to the present invention;

FIGS. 3 and 4 are graphic representations of the temperatureconditionsin the heating tubes of FIGS. 1 and 2, respectively; and

FIGS. 5 and 6 are sectional views illustrating the tube withlongitudinal ribs.

In FIG. 1, a steel tube 1 (conductivity 43 kcal d T C) ofa wallthickness of 1 mm and an interior diameter of 10 mm is shown. The steeltube 1 is situated in a closed enclosure of squared shape and is sealedin aligned openings 2, 3 of the bottom 4 and of the cover 5,respectively, of the enclosure, the bottom and cover being partiallyshown. The enclosure contains air heated approximately to 230C, whichtransfers its heat to the steel tube 1.

In FIG. 3, the temperature curve T of the interior face of the tube 1 isgraphically shown extending over the whole of its length. Thetemperature curve T has a maximum of 225C somewhat above the middle ofthe tube and diminishes rather sharply towards the tube ends, i.e., toapproximately C towards the bottom of the enclosure, and toapproximately 200C towards the cover of the enclosure. This particulartemperature curve is caused by the accumulation of hot air in the upperpart of the enclosure, and by a certain chimney effect in the relativelywide steel tube. In this tube, an optimal heat transfer is obtained onlyover a part of the tube length so that, at higher yarn speeds, undercertain circumstances, an insufficient heating effect on the yarn isobtained. It will also be appreciated that with such apparatus, thespeed of the advancing yarn is often limited.

In FIG. 2, instead of a usual steel tube, a heating tube 10 of thepresent invention is shown. This tube is also arranged in openings 2, 3of the bottom 4 and of the cover 5, respectively, of an enclosurecontaining air of approximately 230C. The tube 10 consists of aluminum(heat conductivity kcal d T C) and has wall thickness of 4.5 mm and aninterior diameter of 3 mm. In FIG. 4, the temperature curve T on theinner wall of the tube 10 is graphically shown over its whole length. Itwill be seen that the temperature curve T is flatter than the one ofFIG. 3, and the temperature is reduced to approximately 200C at bothtube ends. In the tube 10 of the present invention, because of betterheat conductivity of the aluminum used for the tubes, and because of thelarger wall thickness of the tubes and the smaller inner diameter of thesame, the marked temperature decrease existing in known tubes is avoidedat the lower end of the same so that an optimal heat transfer to theyarn to be treated is possible over substantially the whole length ofthe tube. FIGS. 5 and 6 illustrate a series of longitudinal ribs 11formed integral with the tube in order to facilitate heat transfer fromthe fluid medium to the tube wall. The tube of the present inventionpermits higher yarn speeds without terial, besides aluminum, also othermetals with a heat conductivity of at least 70 kcal d T C may be used,such as copper with a conductivity of 320 kcal d T C or brass which,depending on the type of alloy, includes conductivities of between 70and 100 kcal d T C.

From the foregoing description, it will be seen that the presentinvention overcomes the difficulties noted in respect of presently knownheating tubes, and permits more uniform heating and generally fasteradvance of the yarn, and thus greater overall production speeds.

What is claimed is:

1. Apparatus for heating continuously advancing textile yarns consistingat least partially of synthetic thermoplastic material by means of atube sealed at its ends in an enclosure containing a heated fluidmedium, through which tube the yarn passes in axial direction,characterized in that the tube walls consist of a material with aconductivity of at least 70 kcal c T C, that the interiordiameter of thetube is not more than 4 mm and the tube wall thickness is at least 2.5mm.

2. Apparatus according to claim 1, characterized in that'the tube wallsare made of aluminum.

3. Apparatus according to claim 1, characterized in :that the tube wallsare'made of copper.

4. Apparatus according to claim 1, characterized in that the tube wallsare made of brass.

5. Apparatus according to claim 1, characterized in that the interiortube diameter is 2.5 3.5 mm and the wall thickness is 3 5 mm.

6. Apparatus according to claim 1, characterized in that the outer facesof the tube is are provided with ribs.

7. A heating tube of the class described comprising an elongate bodyhaving walls consisting of a material with a conductivity of at leastkcal d T C, a wall thickness of at least 2.5 mm, and an interiordiameter of not more than 4 mm.

8. A tube according to claim 7, characterized in that its outer surfaceis formed with ribs.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION j Patent No. 3 738,Ol7 Dated ne 12 1973 Inventor s) JOSEF RASCHLE It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 3 change "apparatus of" to apparatus 7 for line 27,change "know" to known Column 3, line 20 change "70 kcal c TC" to 70kcal d 'I'C Column 4, line 12, delete "are".

Signed and sealed this 27th day oi. November 1973.

(SEAL) Attest:

EDWARD M. FLETCHL'R,J'R. RENE D THGTMEYER Attesting vOfficer ActingCOIII'HlISSlOI'lGT of Patents FORM 19 9 069) I I uscoMM-oc 60376-P69 I vQ v.5 covzmwnn minnow; offlc: I969 o-ass-su

1. Apparatus for heating continuously advancing textile yarns consistingat least partially of synthetic thermoplastic material by means of atube sealed at its ends in an enclosure containing a heated fluidmedium, through which tube the yarn passes in axial direction,characterized in that the tube walls consist of a material with aconductivity of at least 70 kcal / c T *C, that the interior diameter ofthe tube is not more than 4 mm and the tube wall thickness is at least2.5 mm.
 2. Apparatus according to claim 1, characterized in that thetube walls are made of aluminum.
 3. Apparatus according to claim 1,characterized in that the tube walls are made of copper.
 4. Apparatusaccording to claim 1, characterized in that the tube walls are made ofbrass.
 5. Apparatus according to claim 1, characterized in that theinterior tube diameter is 2.5 - 3.5 mm and the wall thickness is 3 - 5mm.
 6. Apparatus according to claim 1, characterized in that the outerfaces of the tube is are provided with ribs.
 7. A heating tube of theclass described comprising an elongate body having walls consisting of amaterial with a conductivity of at least 70 kcal / d T *C, a wallthickness of at least 2.5 mm, and an interior diameter of not more than4 mm.
 8. A tube according to claim 7, characterized in that its outersurface is formed with ribs.